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llvm-project/clang/lib/CodeGen/CGDecl.cpp

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//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Decl nodes as LLVM code.
//
//===----------------------------------------------------------------------===//
#include "CGDebugInfo.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "CGBlocks.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Type.h"
using namespace clang;
using namespace CodeGen;
void CodeGenFunction::EmitDecl(const Decl &D) {
switch (D.getKind()) {
case Decl::TranslationUnit:
case Decl::Namespace:
case Decl::UnresolvedUsingTypename:
case Decl::ClassTemplateSpecialization:
case Decl::ClassTemplatePartialSpecialization:
case Decl::TemplateTypeParm:
case Decl::UnresolvedUsingValue:
case Decl::NonTypeTemplateParm:
case Decl::CXXMethod:
case Decl::CXXConstructor:
case Decl::CXXDestructor:
case Decl::CXXConversion:
case Decl::Field:
case Decl::IndirectField:
case Decl::ObjCIvar:
case Decl::ObjCAtDefsField:
case Decl::ParmVar:
case Decl::ImplicitParam:
case Decl::ClassTemplate:
case Decl::FunctionTemplate:
case Decl::TemplateTemplateParm:
case Decl::ObjCMethod:
case Decl::ObjCCategory:
case Decl::ObjCProtocol:
case Decl::ObjCInterface:
case Decl::ObjCCategoryImpl:
case Decl::ObjCImplementation:
case Decl::ObjCProperty:
case Decl::ObjCCompatibleAlias:
case Decl::AccessSpec:
case Decl::LinkageSpec:
case Decl::ObjCPropertyImpl:
case Decl::ObjCClass:
case Decl::ObjCForwardProtocol:
case Decl::FileScopeAsm:
case Decl::Friend:
case Decl::FriendTemplate:
case Decl::Block:
assert(0 && "Declaration not should not be in declstmts!");
case Decl::Function: // void X();
case Decl::Record: // struct/union/class X;
case Decl::Enum: // enum X;
case Decl::EnumConstant: // enum ? { X = ? }
case Decl::CXXRecord: // struct/union/class X; [C++]
case Decl::Using: // using X; [C++]
case Decl::UsingShadow:
case Decl::UsingDirective: // using namespace X; [C++]
case Decl::NamespaceAlias:
case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
case Decl::Label: // __label__ x;
// None of these decls require codegen support.
return;
case Decl::Var: {
const VarDecl &VD = cast<VarDecl>(D);
assert(VD.isLocalVarDecl() &&
"Should not see file-scope variables inside a function!");
return EmitVarDecl(VD);
}
case Decl::Typedef: { // typedef int X;
const TypedefDecl &TD = cast<TypedefDecl>(D);
QualType Ty = TD.getUnderlyingType();
if (Ty->isVariablyModifiedType())
EmitVLASize(Ty);
}
}
}
/// EmitVarDecl - This method handles emission of any variable declaration
/// inside a function, including static vars etc.
void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
switch (D.getStorageClass()) {
case SC_None:
case SC_Auto:
case SC_Register:
return EmitAutoVarDecl(D);
case SC_Static: {
llvm::GlobalValue::LinkageTypes Linkage =
llvm::GlobalValue::InternalLinkage;
// If the function definition has some sort of weak linkage, its
// static variables should also be weak so that they get properly
// uniqued. We can't do this in C, though, because there's no
// standard way to agree on which variables are the same (i.e.
// there's no mangling).
if (getContext().getLangOptions().CPlusPlus)
if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage()))
Linkage = CurFn->getLinkage();
return EmitStaticVarDecl(D, Linkage);
}
case SC_Extern:
case SC_PrivateExtern:
// Don't emit it now, allow it to be emitted lazily on its first use.
return;
}
assert(0 && "Unknown storage class");
}
static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
const char *Separator) {
CodeGenModule &CGM = CGF.CGM;
if (CGF.getContext().getLangOptions().CPlusPlus) {
llvm::StringRef Name = CGM.getMangledName(&D);
return Name.str();
}
std::string ContextName;
if (!CGF.CurFuncDecl) {
// Better be in a block declared in global scope.
const NamedDecl *ND = cast<NamedDecl>(&D);
const DeclContext *DC = ND->getDeclContext();
if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
MangleBuffer Name;
CGM.getBlockMangledName(GlobalDecl(), Name, BD);
ContextName = Name.getString();
}
else
assert(0 && "Unknown context for block static var decl");
} else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) {
llvm::StringRef Name = CGM.getMangledName(FD);
ContextName = Name.str();
} else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
ContextName = CGF.CurFn->getName();
else
assert(0 && "Unknown context for static var decl");
return ContextName + Separator + D.getNameAsString();
}
llvm::GlobalVariable *
CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
const char *Separator,
llvm::GlobalValue::LinkageTypes Linkage) {
QualType Ty = D.getType();
assert(Ty->isConstantSizeType() && "VLAs can't be static");
std::string Name = GetStaticDeclName(*this, D, Separator);
const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), LTy,
Ty.isConstant(getContext()), Linkage,
CGM.EmitNullConstant(D.getType()), Name, 0,
D.isThreadSpecified(), Ty.getAddressSpace());
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
if (Linkage != llvm::GlobalValue::InternalLinkage)
GV->setVisibility(CurFn->getVisibility());
return GV;
}
/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
/// global variable that has already been created for it. If the initializer
/// has a different type than GV does, this may free GV and return a different
/// one. Otherwise it just returns GV.
llvm::GlobalVariable *
CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
llvm::GlobalVariable *GV) {
llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this);
// If constant emission failed, then this should be a C++ static
// initializer.
if (!Init) {
if (!getContext().getLangOptions().CPlusPlus)
CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
else if (Builder.GetInsertBlock()) {
// Since we have a static initializer, this global variable can't
// be constant.
GV->setConstant(false);
EmitCXXGuardedInit(D, GV);
}
return GV;
}
// The initializer may differ in type from the global. Rewrite
// the global to match the initializer. (We have to do this
// because some types, like unions, can't be completely represented
// in the LLVM type system.)
if (GV->getType()->getElementType() != Init->getType()) {
llvm::GlobalVariable *OldGV = GV;
GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
OldGV->isConstant(),
OldGV->getLinkage(), Init, "",
/*InsertBefore*/ OldGV,
D.isThreadSpecified(),
D.getType().getAddressSpace());
GV->setVisibility(OldGV->getVisibility());
// Steal the name of the old global
GV->takeName(OldGV);
// Replace all uses of the old global with the new global
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
OldGV->replaceAllUsesWith(NewPtrForOldDecl);
// Erase the old global, since it is no longer used.
OldGV->eraseFromParent();
}
GV->setInitializer(Init);
return GV;
}
void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
llvm::GlobalValue::LinkageTypes Linkage) {
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage);
// Store into LocalDeclMap before generating initializer to handle
// circular references.
DMEntry = GV;
// We can't have a VLA here, but we can have a pointer to a VLA,
// even though that doesn't really make any sense.
// Make sure to evaluate VLA bounds now so that we have them for later.
if (D.getType()->isVariablyModifiedType())
EmitVLASize(D.getType());
// Local static block variables must be treated as globals as they may be
// referenced in their RHS initializer block-literal expresion.
CGM.setStaticLocalDeclAddress(&D, GV);
// If this value has an initializer, emit it.
if (D.getInit())
GV = AddInitializerToStaticVarDecl(D, GV);
GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
// FIXME: Merge attribute handling.
if (const AnnotateAttr *AA = D.getAttr<AnnotateAttr>()) {
SourceManager &SM = CGM.getContext().getSourceManager();
llvm::Constant *Ann =
CGM.EmitAnnotateAttr(GV, AA,
SM.getInstantiationLineNumber(D.getLocation()));
CGM.AddAnnotation(Ann);
}
if (const SectionAttr *SA = D.getAttr<SectionAttr>())
GV->setSection(SA->getName());
if (D.hasAttr<UsedAttr>())
CGM.AddUsedGlobal(GV);
// We may have to cast the constant because of the initializer
// mismatch above.
//
// FIXME: It is really dangerous to store this in the map; if anyone
// RAUW's the GV uses of this constant will be invalid.
const llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType());
const llvm::Type *LPtrTy = LTy->getPointerTo(D.getType().getAddressSpace());
DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy);
// Emit global variable debug descriptor for static vars.
CGDebugInfo *DI = getDebugInfo();
if (DI) {
DI->setLocation(D.getLocation());
DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D);
}
}
unsigned CodeGenFunction::getByRefValueLLVMField(const ValueDecl *VD) const {
assert(ByRefValueInfo.count(VD) && "Did not find value!");
return ByRefValueInfo.find(VD)->second.second;
}
llvm::Value *CodeGenFunction::BuildBlockByrefAddress(llvm::Value *BaseAddr,
const VarDecl *V) {
llvm::Value *Loc = Builder.CreateStructGEP(BaseAddr, 1, "forwarding");
Loc = Builder.CreateLoad(Loc);
Loc = Builder.CreateStructGEP(Loc, getByRefValueLLVMField(V),
V->getNameAsString());
return Loc;
}
/// BuildByRefType - This routine changes a __block variable declared as T x
/// into:
///
/// struct {
/// void *__isa;
/// void *__forwarding;
/// int32_t __flags;
/// int32_t __size;
/// void *__copy_helper; // only if needed
/// void *__destroy_helper; // only if needed
/// char padding[X]; // only if needed
/// T x;
/// } x
///
const llvm::Type *CodeGenFunction::BuildByRefType(const VarDecl *D) {
std::pair<const llvm::Type *, unsigned> &Info = ByRefValueInfo[D];
if (Info.first)
return Info.first;
QualType Ty = D->getType();
std::vector<const llvm::Type *> Types;
llvm::PATypeHolder ByRefTypeHolder = llvm::OpaqueType::get(getLLVMContext());
// void *__isa;
Types.push_back(Int8PtrTy);
// void *__forwarding;
Types.push_back(llvm::PointerType::getUnqual(ByRefTypeHolder));
// int32_t __flags;
Types.push_back(Int32Ty);
// int32_t __size;
Types.push_back(Int32Ty);
bool HasCopyAndDispose = getContext().BlockRequiresCopying(Ty);
if (HasCopyAndDispose) {
/// void *__copy_helper;
Types.push_back(Int8PtrTy);
/// void *__destroy_helper;
Types.push_back(Int8PtrTy);
}
bool Packed = false;
CharUnits Align = getContext().getDeclAlign(D);
if (Align > getContext().toCharUnitsFromBits(Target.getPointerAlign(0))) {
// We have to insert padding.
// The struct above has 2 32-bit integers.
unsigned CurrentOffsetInBytes = 4 * 2;
// And either 2 or 4 pointers.
CurrentOffsetInBytes += (HasCopyAndDispose ? 4 : 2) *
CGM.getTargetData().getTypeAllocSize(Int8PtrTy);
// Align the offset.
unsigned AlignedOffsetInBytes =
llvm::RoundUpToAlignment(CurrentOffsetInBytes, Align.getQuantity());
unsigned NumPaddingBytes = AlignedOffsetInBytes - CurrentOffsetInBytes;
if (NumPaddingBytes > 0) {
const llvm::Type *Ty = llvm::Type::getInt8Ty(getLLVMContext());
// FIXME: We need a sema error for alignment larger than the minimum of
// the maximal stack alignmint and the alignment of malloc on the system.
if (NumPaddingBytes > 1)
Ty = llvm::ArrayType::get(Ty, NumPaddingBytes);
Types.push_back(Ty);
// We want a packed struct.
Packed = true;
}
}
// T x;
Types.push_back(ConvertTypeForMem(Ty));
const llvm::Type *T = llvm::StructType::get(getLLVMContext(), Types, Packed);
cast<llvm::OpaqueType>(ByRefTypeHolder.get())->refineAbstractTypeTo(T);
CGM.getModule().addTypeName("struct.__block_byref_" + D->getNameAsString(),
ByRefTypeHolder.get());
Info.first = ByRefTypeHolder.get();
Info.second = Types.size() - 1;
return Info.first;
}
namespace {
struct CallArrayDtor : EHScopeStack::Cleanup {
CallArrayDtor(const CXXDestructorDecl *Dtor,
const ConstantArrayType *Type,
llvm::Value *Loc)
: Dtor(Dtor), Type(Type), Loc(Loc) {}
const CXXDestructorDecl *Dtor;
const ConstantArrayType *Type;
llvm::Value *Loc;
void Emit(CodeGenFunction &CGF, bool IsForEH) {
QualType BaseElementTy = CGF.getContext().getBaseElementType(Type);
const llvm::Type *BasePtr = CGF.ConvertType(BaseElementTy);
BasePtr = llvm::PointerType::getUnqual(BasePtr);
llvm::Value *BaseAddrPtr = CGF.Builder.CreateBitCast(Loc, BasePtr);
CGF.EmitCXXAggrDestructorCall(Dtor, Type, BaseAddrPtr);
}
};
struct CallVarDtor : EHScopeStack::Cleanup {
CallVarDtor(const CXXDestructorDecl *Dtor,
llvm::Value *NRVOFlag,
llvm::Value *Loc)
: Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(Loc) {}
const CXXDestructorDecl *Dtor;
llvm::Value *NRVOFlag;
llvm::Value *Loc;
void Emit(CodeGenFunction &CGF, bool IsForEH) {
// Along the exceptions path we always execute the dtor.
bool NRVO = !IsForEH && NRVOFlag;
llvm::BasicBlock *SkipDtorBB = 0;
if (NRVO) {
// If we exited via NRVO, we skip the destructor call.
llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
CGF.EmitBlock(RunDtorBB);
}
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
/*ForVirtualBase=*/false, Loc);
if (NRVO) CGF.EmitBlock(SkipDtorBB);
}
};
}
namespace {
struct CallStackRestore : EHScopeStack::Cleanup {
llvm::Value *Stack;
CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
void Emit(CodeGenFunction &CGF, bool IsForEH) {
llvm::Value *V = CGF.Builder.CreateLoad(Stack, "tmp");
llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
CGF.Builder.CreateCall(F, V);
}
};
struct CallCleanupFunction : EHScopeStack::Cleanup {
llvm::Constant *CleanupFn;
const CGFunctionInfo &FnInfo;
const VarDecl &Var;
CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
const VarDecl *Var)
: CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
void Emit(CodeGenFunction &CGF, bool IsForEH) {
DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue,
SourceLocation());
// Compute the address of the local variable, in case it's a byref
// or something.
llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
// In some cases, the type of the function argument will be different from
// the type of the pointer. An example of this is
// void f(void* arg);
// __attribute__((cleanup(f))) void *g;
//
// To fix this we insert a bitcast here.
QualType ArgTy = FnInfo.arg_begin()->type;
llvm::Value *Arg =
CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
CallArgList Args;
Args.push_back(std::make_pair(RValue::get(Arg),
CGF.getContext().getPointerType(Var.getType())));
CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
}
};
struct CallBlockRelease : EHScopeStack::Cleanup {
llvm::Value *Addr;
CallBlockRelease(llvm::Value *Addr) : Addr(Addr) {}
void Emit(CodeGenFunction &CGF, bool IsForEH) {
CGF.BuildBlockRelease(Addr, BLOCK_FIELD_IS_BYREF);
}
};
}
/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
/// non-zero parts of the specified initializer with equal or fewer than
/// NumStores scalar stores.
static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
unsigned &NumStores) {
// Zero and Undef never requires any extra stores.
if (isa<llvm::ConstantAggregateZero>(Init) ||
isa<llvm::ConstantPointerNull>(Init) ||
isa<llvm::UndefValue>(Init))
return true;
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
isa<llvm::ConstantExpr>(Init))
return Init->isNullValue() || NumStores--;
// See if we can emit each element.
if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
return false;
}
return true;
}
// Anything else is hard and scary.
return false;
}
/// emitStoresForInitAfterMemset - For inits that
/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
/// stores that would be required.
static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
bool isVolatile, CGBuilderTy &Builder) {
// Zero doesn't require any stores.
if (isa<llvm::ConstantAggregateZero>(Init) ||
isa<llvm::ConstantPointerNull>(Init) ||
isa<llvm::UndefValue>(Init))
return;
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
isa<llvm::ConstantExpr>(Init)) {
if (!Init->isNullValue())
Builder.CreateStore(Init, Loc, isVolatile);
return;
}
assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
"Unknown value type!");
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
if (Elt->isNullValue()) continue;
// Otherwise, get a pointer to the element and emit it.
emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
isVolatile, Builder);
}
}
/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
/// plus some stores to initialize a local variable instead of using a memcpy
/// from a constant global. It is beneficial to use memset if the global is all
/// zeros, or mostly zeros and large.
static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
uint64_t GlobalSize) {
// If a global is all zeros, always use a memset.
if (isa<llvm::ConstantAggregateZero>(Init)) return true;
// If a non-zero global is <= 32 bytes, always use a memcpy. If it is large,
// do it if it will require 6 or fewer scalar stores.
// TODO: Should budget depends on the size? Avoiding a large global warrants
// plopping in more stores.
unsigned StoreBudget = 6;
uint64_t SizeLimit = 32;
return GlobalSize > SizeLimit &&
canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
}
/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
/// variable declaration with auto, register, or no storage class specifier.
/// These turn into simple stack objects, or GlobalValues depending on target.
void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
AutoVarEmission emission = EmitAutoVarAlloca(D);
EmitAutoVarInit(emission);
EmitAutoVarCleanups(emission);
}
/// EmitAutoVarAlloca - Emit the alloca and debug information for a
/// local variable. Does not emit initalization or destruction.
CodeGenFunction::AutoVarEmission
CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
QualType Ty = D.getType();
AutoVarEmission emission(D);
bool isByRef = D.hasAttr<BlocksAttr>();
emission.IsByRef = isByRef;
CharUnits alignment = getContext().getDeclAlign(&D);
emission.Alignment = alignment;
llvm::Value *DeclPtr;
if (Ty->isConstantSizeType()) {
if (!Target.useGlobalsForAutomaticVariables()) {
bool NRVO = getContext().getLangOptions().ElideConstructors &&
D.isNRVOVariable();
// If this value is a POD array or struct with a statically
// determinable constant initializer, there are optimizations we
// can do.
// TODO: we can potentially constant-evaluate non-POD structs and
// arrays as long as the initialization is trivial (e.g. if they
// have a non-trivial destructor, but not a non-trivial constructor).
if (D.getInit() &&
(Ty->isArrayType() || Ty->isRecordType()) && Ty->isPODType() &&
D.getInit()->isConstantInitializer(getContext(), false)) {
// If the variable's a const type, and it's neither an NRVO
// candidate nor a __block variable, emit it as a global instead.
if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() &&
!NRVO && !isByRef) {
EmitStaticVarDecl(D, llvm::GlobalValue::PrivateLinkage);
emission.Address = 0; // signal this condition to later callbacks
assert(emission.wasEmittedAsGlobal());
return emission;
}
// Otherwise, tell the initialization code that we're in this case.
emission.IsConstantAggregate = true;
}
// A normal fixed sized variable becomes an alloca in the entry block,
// unless it's an NRVO variable.
const llvm::Type *LTy = ConvertTypeForMem(Ty);
if (NRVO) {
// The named return value optimization: allocate this variable in the
// return slot, so that we can elide the copy when returning this
// variable (C++0x [class.copy]p34).
DeclPtr = ReturnValue;
if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
// Create a flag that is used to indicate when the NRVO was applied
// to this variable. Set it to zero to indicate that NRVO was not
// applied.
llvm::Value *Zero = Builder.getFalse();
llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
EnsureInsertPoint();
Builder.CreateStore(Zero, NRVOFlag);
// Record the NRVO flag for this variable.
NRVOFlags[&D] = NRVOFlag;
emission.NRVOFlag = NRVOFlag;
}
}
} else {
if (isByRef)
LTy = BuildByRefType(&D);
llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
Alloc->setName(D.getNameAsString());
CharUnits allocaAlignment = alignment;
if (isByRef)
allocaAlignment = std::max(allocaAlignment,
getContext().toCharUnitsFromBits(Target.getPointerAlign(0)));
Alloc->setAlignment(allocaAlignment.getQuantity());
DeclPtr = Alloc;
}
} else {
// Targets that don't support recursion emit locals as globals.
const char *Class =
D.getStorageClass() == SC_Register ? ".reg." : ".auto.";
DeclPtr = CreateStaticVarDecl(D, Class,
llvm::GlobalValue::InternalLinkage);
}
// FIXME: Can this happen?
if (Ty->isVariablyModifiedType())
EmitVLASize(Ty);
} else {
EnsureInsertPoint();
if (!DidCallStackSave) {
// Save the stack.
llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
llvm::Value *V = Builder.CreateCall(F);
Builder.CreateStore(V, Stack);
DidCallStackSave = true;
// Push a cleanup block and restore the stack there.
// FIXME: in general circumstances, this should be an EH cleanup.
EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack);
}
// Get the element type.
const llvm::Type *LElemTy = ConvertTypeForMem(Ty);
const llvm::Type *LElemPtrTy = LElemTy->getPointerTo(Ty.getAddressSpace());
llvm::Value *VLASize = EmitVLASize(Ty);
// Allocate memory for the array.
llvm::AllocaInst *VLA =
Builder.CreateAlloca(llvm::Type::getInt8Ty(getLLVMContext()), VLASize, "vla");
VLA->setAlignment(alignment.getQuantity());
DeclPtr = Builder.CreateBitCast(VLA, LElemPtrTy, "tmp");
}
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
DMEntry = DeclPtr;
emission.Address = DeclPtr;
// Emit debug info for local var declaration.
if (CGDebugInfo *DI = getDebugInfo()) {
assert(HaveInsertPoint() && "Unexpected unreachable point!");
DI->setLocation(D.getLocation());
if (Target.useGlobalsForAutomaticVariables()) {
DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D);
} else
DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
}
return emission;
}
/// Determines whether the given __block variable is potentially
/// captured by the given expression.
static bool isCapturedBy(const VarDecl &var, const Expr *e) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
e = e->IgnoreParenCasts();
if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
const BlockDecl *block = be->getBlockDecl();
for (BlockDecl::capture_const_iterator i = block->capture_begin(),
e = block->capture_end(); i != e; ++i) {
if (i->getVariable() == &var)
return true;
}
// No need to walk into the subexpressions.
return false;
}
for (Stmt::const_child_range children = e->children(); children; ++children)
if (isCapturedBy(var, cast<Expr>(*children)))
return true;
return false;
}
void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
const VarDecl &D = *emission.Variable;
QualType type = D.getType();
// If this local has an initializer, emit it now.
const Expr *Init = D.getInit();
// If we are at an unreachable point, we don't need to emit the initializer
// unless it contains a label.
if (!HaveInsertPoint()) {
if (!Init || !ContainsLabel(Init)) return;
EnsureInsertPoint();
}
CharUnits alignment = emission.Alignment;
if (emission.IsByRef) {
llvm::Value *V;
BlockFieldFlags fieldFlags;
bool fieldNeedsCopyDispose = false;
if (type->isBlockPointerType()) {
fieldFlags |= BLOCK_FIELD_IS_BLOCK;
fieldNeedsCopyDispose = true;
} else if (getContext().isObjCNSObjectType(type) ||
type->isObjCObjectPointerType()) {
fieldFlags |= BLOCK_FIELD_IS_OBJECT;
fieldNeedsCopyDispose = true;
} else if (getLangOptions().CPlusPlus) {
if (getContext().getBlockVarCopyInits(&D))
fieldNeedsCopyDispose = true;
else if (const CXXRecordDecl *record = type->getAsCXXRecordDecl())
fieldNeedsCopyDispose = !record->hasTrivialDestructor();
}
llvm::Value *addr = emission.Address;
// FIXME: Someone double check this.
if (type.isObjCGCWeak())
fieldFlags |= BLOCK_FIELD_IS_WEAK;
// Initialize the 'isa', which is just 0 or 1.
int isa = 0;
if (fieldFlags & BLOCK_FIELD_IS_WEAK)
isa = 1;
V = Builder.CreateIntToPtr(Builder.getInt32(isa), Int8PtrTy, "isa");
Builder.CreateStore(V, Builder.CreateStructGEP(addr, 0, "byref.isa"));
// Store the address of the variable into its own forwarding pointer.
Builder.CreateStore(addr,
Builder.CreateStructGEP(addr, 1, "byref.forwarding"));
// Blocks ABI:
// c) the flags field is set to either 0 if no helper functions are
// needed or BLOCK_HAS_COPY_DISPOSE if they are,
BlockFlags flags;
if (fieldNeedsCopyDispose) flags |= BLOCK_HAS_COPY_DISPOSE;
Builder.CreateStore(llvm::ConstantInt::get(IntTy, flags.getBitMask()),
Builder.CreateStructGEP(addr, 2, "byref.flags"));
const llvm::Type *V1;
V1 = cast<llvm::PointerType>(addr->getType())->getElementType();
V = llvm::ConstantInt::get(IntTy, CGM.GetTargetTypeStoreSize(V1).getQuantity());
Builder.CreateStore(V, Builder.CreateStructGEP(addr, 3, "byref.size"));
if (fieldNeedsCopyDispose) {
llvm::Value *copy_helper = Builder.CreateStructGEP(addr, 4);
Builder.CreateStore(CGM.BuildbyrefCopyHelper(addr->getType(), fieldFlags,
alignment.getQuantity(), &D),
copy_helper);
llvm::Value *destroy_helper = Builder.CreateStructGEP(addr, 5);
Builder.CreateStore(CGM.BuildbyrefDestroyHelper(addr->getType(),
fieldFlags,
alignment.getQuantity(),
&D),
destroy_helper);
}
}
if (!Init) return;
// Check whether this is a byref variable that's potentially
// captured and moved by its own initializer. If so, we'll need to
// emit the initializer first, then copy into the variable.
bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
llvm::Value *Loc =
capturedByInit ? emission.Address : emission.getObjectAddress(*this);
bool isVolatile = type.isVolatileQualified();
// If this is a simple aggregate initialization, we can optimize it
// in various ways.
if (emission.IsConstantAggregate) {
assert(!capturedByInit && "constant init contains a capturing block?");
llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), type, this);
assert(Init != 0 && "Wasn't a simple constant init?");
llvm::Value *SizeVal =
llvm::ConstantInt::get(IntPtrTy,
getContext().getTypeSizeInChars(type).getQuantity());
const llvm::Type *BP = Int8PtrTy;
if (Loc->getType() != BP)
Loc = Builder.CreateBitCast(Loc, BP, "tmp");
// If the initializer is all or mostly zeros, codegen with memset then do
// a few stores afterward.
if (shouldUseMemSetPlusStoresToInitialize(Init,
CGM.getTargetData().getTypeAllocSize(Init->getType()))) {
Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
alignment.getQuantity(), isVolatile);
if (!Init->isNullValue()) {
Loc = Builder.CreateBitCast(Loc, Init->getType()->getPointerTo());
emitStoresForInitAfterMemset(Init, Loc, isVolatile, Builder);
}
} else {
// Otherwise, create a temporary global with the initializer then
// memcpy from the global to the alloca.
std::string Name = GetStaticDeclName(*this, D, ".");
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), Init->getType(), true,
llvm::GlobalValue::InternalLinkage,
Init, Name, 0, false, 0);
GV->setAlignment(alignment.getQuantity());
llvm::Value *SrcPtr = GV;
if (SrcPtr->getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
isVolatile);
}
} else if (type->isReferenceType()) {
RValue RV = EmitReferenceBindingToExpr(Init, &D);
if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D);
EmitStoreOfScalar(RV.getScalarVal(), Loc, false, alignment.getQuantity(),
type);
} else if (!hasAggregateLLVMType(type)) {
llvm::Value *V = EmitScalarExpr(Init);
if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D);
EmitStoreOfScalar(V, Loc, isVolatile, alignment.getQuantity(), type);
} else if (type->isAnyComplexType()) {
ComplexPairTy complex = EmitComplexExpr(Init);
if (capturedByInit) Loc = BuildBlockByrefAddress(Loc, &D);
StoreComplexToAddr(complex, Loc, isVolatile);
} else {
// TODO: how can we delay here if D is captured by its initializer?
EmitAggExpr(Init, AggValueSlot::forAddr(Loc, isVolatile, true, false));
}
}
void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
const VarDecl &D = *emission.Variable;
// Handle C++ destruction of variables.
if (getLangOptions().CPlusPlus) {
QualType type = D.getType();
QualType baseType = getContext().getBaseElementType(type);
if (const RecordType *RT = baseType->getAs<RecordType>()) {
CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
if (!ClassDecl->hasTrivialDestructor()) {
// Note: We suppress the destructor call when the corresponding NRVO
// flag has been set.
// Note that for __block variables, we want to destroy the
// original stack object, not the possible forwarded object.
llvm::Value *Loc = emission.getObjectAddress(*this);
const CXXDestructorDecl *D = ClassDecl->getDestructor();
assert(D && "EmitLocalBlockVarDecl - destructor is nul");
if (type != baseType) {
const ConstantArrayType *Array =
getContext().getAsConstantArrayType(type);
assert(Array && "types changed without array?");
EHStack.pushCleanup<CallArrayDtor>(NormalAndEHCleanup,
D, Array, Loc);
} else {
EHStack.pushCleanup<CallVarDtor>(NormalAndEHCleanup,
D, emission.NRVOFlag, Loc);
}
}
}
}
// Handle the cleanup attribute.
if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
const FunctionDecl *FD = CA->getFunctionDecl();
llvm::Constant *F = CGM.GetAddrOfFunction(FD);
assert(F && "Could not find function!");
const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD);
EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
}
// If this is a block variable, call _Block_object_destroy
// (on the unforwarded address).
if (emission.IsByRef &&
CGM.getLangOptions().getGCMode() != LangOptions::GCOnly)
EHStack.pushCleanup<CallBlockRelease>(NormalAndEHCleanup, emission.Address);
}
/// Emit an alloca (or GlobalValue depending on target)
/// for the specified parameter and set up LocalDeclMap.
void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg) {
// FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
"Invalid argument to EmitParmDecl");
Arg->setName(D.getName());
// Use better IR generation for certain implicit parameters.
if (isa<ImplicitParamDecl>(D)) {
// The only implicit argument a block has is its literal.
if (BlockInfo) {
LocalDeclMap[&D] = Arg;
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(D.getLocation());
DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
}
return;
}
}
QualType Ty = D.getType();
llvm::Value *DeclPtr;
// If this is an aggregate or variable sized value, reuse the input pointer.
if (!Ty->isConstantSizeType() ||
CodeGenFunction::hasAggregateLLVMType(Ty)) {
DeclPtr = Arg;
} else {
// Otherwise, create a temporary to hold the value.
DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr");
// Store the initial value into the alloca.
EmitStoreOfScalar(Arg, DeclPtr, Ty.isVolatileQualified(),
getContext().getDeclAlign(&D).getQuantity(), Ty,
CGM.getTBAAInfo(Ty));
}
llvm::Value *&DMEntry = LocalDeclMap[&D];
assert(DMEntry == 0 && "Decl already exists in localdeclmap!");
DMEntry = DeclPtr;
// Emit debug info for param declaration.
if (CGDebugInfo *DI = getDebugInfo()) {
DI->setLocation(D.getLocation());
DI->EmitDeclareOfArgVariable(&D, DeclPtr, Builder);
}
}
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